SVN error: (501 Not Implemented)

Hey,
I'm trying to create a branches directory for our project:
svn mkdir -m "Creating branches directory" http://local.domain/OoProject/branches But I got this error:
svn: Server sent unexpected return value (501 Not Implemented) in response to OPTIONS request for 'http://local.domain/OoProject'
I googled, it is a firewall issue.
local.domain isn't guarded via a firewall.
I turned the firewall off on my Mac client, but I got the same error.
Any ideas?
Thanks for help and time.